It is known to provide a torsional vibration damper for an engine crankshaft in which a rotary body incorporates a plurality of steel springs interconnecting inner and outer body members for relative rotation with a desired stiffness. Damping is achieved by pumping engine oil between different cavities within the damper construction. U.S. Pat. No. 3,996,767 is an example of this type of damper. Such dampers are likely to require the complex assembly of many precision-machined parts which make them inherently expensive. U.S. patent application Ser. No. 805,346, filed on Dec. 9, 1991 and of common assignment with the present invention, proposes a more economical damper construction but still utilizes a multiplicity of steel springs.
It is an object of the present invention to provide a torsional vibration damper in which the above disadvantage is obviated or mitigated.